Reagan's Coattails Look Short For '86

WASHINGTON — A political consultant who played a prominent role in President Reagan's campaign now privately advises his Republican clients that ''they need to show some independence'' from Reagan in their Senate and House campaigns.

One lesson that political professionals have learned is that Reagan's popularity with the voters doesn't necessarily translate into support for his position on particular issues such as tax reform, trade, farm problems and South Africa.

And if there is a more general lesson they have learned about the politics of the 1980s it is that independence is more highly prized by the voter than blind adherence to any ideological line.

The evidence is abundant. In that special congressional election in Texas last month, to cite one example, the Republicans based their case for Edd Hargett on his promise to be a devoted Reaganite -- and in a district in which the president's popularity had soared in the immediate aftermath of his cancer surgery. As it turned out, however, that wasn't enough to counter the Democrats' exploitation of the Social Security and trade questions.

In Iowa, to cite another case, Republican Sen. Charles Grassley is considered virtually invulnerable next year despite the condition of the farm economy because he has made such a point of standing apart from the White House on visible issues.

There is no question that Reagan has broad support, for example, on the general thrust of his campaign to reduce spending and the role of the federal government in American life.

But much of Reagan's remarkable strength is based on his persona; the voters like him even when they disagree with him on specifics. That is what makes him such a political phenomenon.

Thus, prudent politicians understand that, as one operative put, ''Reagan- bashing is very dangerous'' for either Democrats or Republicans. There is, however, a significant difference between trashing the president and standing apart from him on particular issues, and this is something White House advisers seem to have trouble understanding.

The Social Security issue is a classic case in point. Reagan is widely perceived as a president willing to tinker with benefits and, despite all his protests to the contrary, that perception is accurate and based on considerable evidence dating back more than 20 years. So a Republican running in a state with a large population of the elderly -- such as Florida, Iowa or Missouri -- would be well-advised to establish his own bona fides on the issue.

Beyond that, most of the issues on the front burner right now -- trade, the farm bill and South Africa, most notably -- obviously have special constituencies in many states and many congressional districts. And in those cases, the politician who goes down the line with Reagan simply because of the president's popularity is risking disaster.